Device for sealing-off metal tanks



March 3, '@36., W. A, wiLKiNs DEVICE FOR SEALING-OFF METAL TANKS FiledJuly 29, 1952 Inventor: William Awilkins,

by Mx His Attorney.

Patented Mar. 3, 1936 y I, n l 2,032,862

DEVICE FOR SEALING-OFF METAL TANKS William A. Wilkins, Schenectady, N.Y., assignor to General Electric C New York ompany, a corporation oi'Application July 29, 1932,. Serial No. 626,053 i 2 claims. (c1.:ats-Q82)V The present invention relates to electric discharge apparatusand more particularly to devices for sealing evacuated envelopes whichcontain said apparatus.

devices, such as mercury-arc rectifier It is customary to use largemetal tanks as envelopes for certain types of power-translating s, etc.and

these tanks are evacuated and sealed off from the pump.

the metal tank which is drawn down haust tube and sealed off when theevacuation.

This blown glass seal is process is complete.

In order to facilitate sealing, it is customary to provide a blown glassportion on to an exvery fragile and presents a structural weakness in anotherwise rugged apparatus.

entirely by a metal member.

In brief, my in- 'vention contemplates the use of a sealing device whichis temporarily secured to the metal tank or container and which forces acopper or other metal plug into an exhaust opening in the tank when theevacuation is complete.

The invention will be better understood when reference is made to thefollowing descriptionv and the accompanying drawing in which Fig. 1shows a longitudinal section of the improved sealing device and Fig. 2illustrates an elevational view of the device.

Numeral I designates a portion of a metal tank, the interior of which isto be evacuated.

An opening, preferably circular in form, is provided in the tank and tothis opening, covering the same, there is secured, preferably bywelding, a circular steel flange member 2 provided with a threadedupstanding projection 3 which contains an exhaust opening 4.

This opening is preferably chamfered as indicated at 5 on the interiorof the tank and is slightly tapered, with the opening of smallerdiameter nearer the tank.

The improved sealing device is constituted of a metal member 6, theexterior surface of which may be cut to a hexagonal shape in order topermit the application of a wrench for purposes as will appearhereinafter. a longitudinal opening consisting of The member 6 has twocentral bores of different diameter, the larger bore being of the samediameter as the opening in the flange member 3. The member 6 is providedat one end with an extension 1, threaded on the interior and adapted tobe screwe threaded steel flange. tending transversely of the member 6municating with the central bore.

d ontoy the There is an opening exand com- Into this opening is drivena'steel tubing 8, slightly chamfered at the inner end and tapering atthe other end to make a close contact with a rubber hose (not shown),`aswill be explained presently. The upper end of the hexagonal member6, as shown, 5 is turned downto form a seat 9 for a piece of extensiblemetal tubing I0 such as sylphon or the like, while'the interior of themetal member 6 at this end is chamfered, as indicated by referencecharacter II. The member I0 at the top, 10 carries a metal cap I2 whichis provided with a threaded bore' I3. This cap is fitted tightly tothe'tubing I0 by means of a turned-down seat I4 and is chamfered on theinterior as indicated by reference character I5. There is secured in 15the threaded bore I3, a centrally disposed metal ram I6 which 'extendsdownwardly, as shown, through the bore of smaller diameter in the metalpiece 6 and terminates slightly beyond the annular. shoulder formedbetween the two bores 20 of the member 6. The lower end of the ram I6carries a. spring wire holder I1 in any convient manner, as for exampleby a hinge and over ythis holder there is forced a round sealing plug I8of a relatively soft metal, such as chro- 25 lilium-plated copper. Theplug is drilled at the surface which, contacts with the ram I6, the holebeing of a size sufficiently small to permit the plug to be pressedtightly over the holder Il and to be securely attached thereto.

When it is desired to operate the device and the sealing plug I8 hasbeen secured to the end of the ram, the sylphon tube I8 is stretchedupwardly and held in that position until it is time to force the sealingplug into the opening of the 35 steel flange. In order to maintain thetubing in this position, there is provided a pair of metal arms I9positioned on opposite sides of the metal member 6 and pivoted at theirlower ends to this member about the screws 20. The upper 40 ends ofthese arms are cut ilat and horizontal, as shown, and are adapted tobear against or engage the lower surface of a circular flange providedon the cap member I2. The length of these arms I9 should be such as tohold the sylphon tubing in the extended position carrying with it, theram I6 and the attached plug I8. It is apparent that when the device isin this position, the plug I8 is held away from the 50 opening 4 and thepreferable arrangement is such that the plug I8, in its upper position,completely uncovers the opening in the horizontallyextending tube 8. Thearms I9 are preferably connected together in any suitable manner, for 55example, by an arcuate strip or yoke 2| of metal which serves as acombined support and handle. In order to operate the device, after asealing plug has been placed on the spring Wire holder, the device isscrewed down firmly onto the threaded portion of the flange 3, a coppergasket 22 being used to provide a more intimate contact. A'rubber hose(not shown) is then forced on the tapered tubing or nipple 8 and thetank l evacuated in the usual manner. vacuum has been obtained, and inthe case o f gas or vapor devices, after the gas or vapor has beenintroduced, the double-armed lever I9 is released by moving the yoke 2|to the left as shown in Fig. 2, and the atmospheric pressure operatingon the cap I2 causes the sylphon to collapse and to force the sealingplug into the opening of the steel nange. In order to prevent the leverfrom moving a distance more than is necessary, i. e. so that it willjust simply clear the cap l2, stop pins 23 may be provided on oppositesides of the member .6. There is also a pair of pins 24 located near thepins 23 to limit the movementof the arms I9 in the other direction. Y Y

Whenthe plug I8 has been rmly seated in Vthe openings, the cap l2 ispreferably struck several blows with a hammer in order to complete theseal'between the plug andthe opening. These hammer blows arecommunicated to the plug through the ram I6. The sealing device may thenbe unscrewed from the tank. As an added precaution, the top of thesealing plusr and iiange may besoldered.

From the foregoing, it isY evident that I have disclosedV a sealingdevice which employs allmetal parts and necessitates in its use, simplya metal flange member welded to the Ytank and provided with threads. Theimproved arrangement eliminates the need for any glass seals andconsequently, permits the manufacture of highly evacuated all-metaltanks which contain electrical apparatus, electrodes, etc. .Y

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A device for sealing off an evacuated metal tank provided with anopening, said device com- After the properV prising means for holding asealing plug at a position remote from said opening but in linetherewith, said means comprising a hollow metal member which iits overthe tank opening, and a collapsible air-tight member which closes theopening in said metal member and which carries the sealing plug, theinterior of said member being subjected to the rareed conditions in thetank and the exterior of said member being eX- posed to the atmosphereand means for releasing the holding means whereby the sealing plug ispermitted to move toward the tank and to be forced into the opening byatmospheric pressure, said releasing means comprising aY pair ofinterconnected arms rotatably mounted on opposite sides of said hollowmetal member and adapted to be moved from a position in which theyengage the collapsible member toV a position entirely free of saidmember.

2. Apparatus for forcinga sealing plug into an opening in an evacuatedmetal tank, said apparatus comprising in combination, a metal memberhaving a central aperture and adapted to be secured to the tank in line4with said opening, a collapsible metal tubing secured to said member andclosed at the end remote from the tank by a cap whereby the interior ofsaid tubing is subjected to the rareed conditions of the tank and theexterior of said tubing is exposed to the atmosphere, a rod secured tosaid capV and extending through the aperture in said member, said rodbeing adapted to receive a sealing plug which is temporarily positionedWithin the interior of said metal member in line with the opening insaid tank, an evacuating conduit secured to said member andcommunicating with the interior of the tank, a pair of interconnectedarms mounted on opposite sides of said member, saidarms being of alength suicient to engage said cap and to hold the collapsible tubing inan extended position, said arms being adapt- Y

